Gagal Update data

halo master saya mau nanya ketika update data knapa ga bisa ya? berikut kodingannya terima kasih

<?php
include "koneksi.php";
$kode                   = $_POST['sid'];
$pe                     = $_POST['pe'];
$subint                 = $_POST['subint'];
$link_tipe              = $_POST['link_tipe'];
$vrf                    = $_POST['vrf'];
$ipce                   = $_POST['ipce'];
$venue_name             = $_POST['venue_name'];

    $query = mysql_query("UPDATE `a_circuit_critical` SET `pe` = '$pe', `subint` = '$subint', `link_tipe` = '$link_tipe', `vrf` = '$vrf', `ipce` = '$ipce', `venue_name` = '$venue_name' WHERE `a_circuit_critical`.`sid` = 'kode'");

    if($query){
    ?>
    <?php
    echo '<script language="javascript">alert("Data Berhasil Diperbahurui"); document.location="index.php";</script>';
    }
    else{
        echo "gagal diperbahurui";
    }

?>